Minimize particle movement during repartitioning

Attempt to keep particles on local nodes by comparing the new and old regions and permuting the solution by picking new regions with the largest number of cells in the old regions. Gives an unmoved fraction of around 42% for larger numbers of ranks (compared to 1/nrank for the current scheme).

Doesn't make a huge improvement to runtimes, seems to be around 10% on a repartition step of EAGLE_25, and we only do that infrequently.

Title changed from WIP: Minimize particle movement during repartitioning to Minimize particle movement during repartitioning

Reassigned to @nnrw56

Added 1 commit:

• 19f735d0 - format.sh applied

Just some documentation issues, otherwise looks good!

Added 1 commit:

• b91a5ff3 - Improve descriptive content

Added some changes that hopefully address your concerns. Good to go now?

Good to go, thanks for implementing this!

Reassigned to @pdraper

Status changed to merged

mentioned in commit 290e85f7